Beta-alkyl-thio acrolein mercaptals



Patented Dec. 17, 1946 OFFICE ,nETA-sLxYn-Tmo ACROLEIN MERCAPTALS John David Kendall and Harry Derek Edwards, Ilford, England, assignors to Iliord Limited, Ilford, England, a British Company No Drawing. Application December (1943, geiiggaNo. 514,666. In Great Britain January 20lairns. (01.260-609) l i This invention relates to the production of or ganic compounds which are useful as intermediates for the formation of dyestuffs, and to the organic compoundsso produced. 1 a According to the present invention organi compounds of the general Formula I:

... v sa' 1" where R is an allqvl group, are obtained by treat:

ing' with an alkylmercaptan, in the presence of an acid condensing agent, a compound of one of the Formulae II, III, IV or V:

or by treating with an alkyl mercaptan in the presence of a basic condensing agent under pressure, a compound of Formula II.

Compounds of the general Formula II may be obtained by brominating acrolein and treating the product with an alkyl mercaptan followed by heating with an alkali to remove bromine.- Compounds of general Formula III may be converted to compounds .of general Formula V by treating them with a sodium alkyl mercaptide and an alkyl mercaptan under pressure.

Beta-alkyl-thio acrolein di-alkyl mercaptais can be made by treating a compound of Formula II in which the groups R are alkyl groups with alkyl mercaptan in the presence of a basic condensing agent under pressure.

The most convenient compound of general For- 'mula I to prepare is that in which the groups R are ethyl groups since ethyl mercaptan is the most convenient of the allq/l mercaptans to employ. In using the compounds of general Formula I as dyestufi intermediates the condensation .to produce dyestufl's may eliminate all the -873.

groups so that the nature of the R group is not then of importance.

Theacid condensing agent may be any strongly acidic substance; sulphuric acid and zinc chloride have been found very suitable.

The following examples illustrate the invention, as applied to the production of the coma pound p-ethyl thio acrolein diethyi mercaptal.

' Exsuru: I

(a) Preparation of mam: aldehyde diethyl mercaptaljrom acrolein 100 grams of acrolein was cooled to about 5 C.

and 90ccs. oi bromine added dropwise, with good shaking, over. about 2 hours. 5 gm's. of sodium bicarbonate was added and the mixture left overnight. The acrolein dibromide was filtered and then added slowly to 260 gms. of ethyl mercantanywith stirring and cooling so that the temperature was kept below 10 C. The reaction mixture was then allowed to stand for two hours at room temperature. 5 gms. oi sodium bicarbonate was then added and the mixture allowed to stand overnight. A solution of 200 guns. of caustic potash in 900 ccs. ethyl alcohol was prepared and the reaction mixture (now containing P acrolein dibromide mercaptaD' added slowly at a temperature of about '30-40 C. The mixture was then boiled under reflux for hour. The alcohol was then distilled oil through a' partial condried over sodium carbonate. The ether was dis- V 1 tilled oil and the residue distilled in vacuo. The

product contained a trace of bromine which was removed by boiling under reflux with '5 gms. sodium mercaptide in ccs. alcohol for /2 hour. The alcohol was distilled oil, the residue poured into water, ether-extracted and distilled as before, giving the product as an oil. 13. P, C.

at 10 mm. pressure.

(b) Preparation of p-ethul-thio acrolein'diethul mercaptal from proparwl aldehyde diethyl mercaptal v80 gms. of propargyl aldehyde diethyl mercapta1,75 cos. of ethylmercaptan and 68 guns. of anhydrous zinc chloride were mixed in the cold and allowed to stand for two days, after which the mixture was poured on to cracked ice, and treated with a little dilute acid. The oil obtained was separated from the aqueous liquors, which were extracted with ether. The oil and ether extracts were bulked'and well washed with water, followed by sodlum carbonate solution, and finally dried over potassium carbonate. The solution was filtered and the ether distilled off. The residual oil was distilled in vacuo, collecting fractions (1) up to 120 C., (2) 120-160 C., (3) 160-- 195 C. Distillates (2) and (3) were redistilled fractionally from a sulphuric acid bath to give the product boiling at 185-192 C. at 6 mm.

pressure.

(0) Alternative preparation of p-ethyl-thio acroleindiethyl mercaptal from propargyl aldehyde diethyl mercaptal 53 gms. of propargyl aldehyde diethyl mercaptal, 50ccs. of ethyl mercaptan and 5 drops of concentrated sulphuric acid were mixed in the cold and allowed to stand for a week. The acid layer was then separated off and the oil well washed with water and dried over potassium carbonate.

After filtering, the excess ethyl mercaptan was distilled 01f from a water bath and the residue distilled in vacuo, separating into three fractions which were redistilled to give the product boiling at 168-190 C. at 6 mm. pressure.

EXAMPLE II (a) Preparation of p-ethyl-thio acrolein diethyl acetal from propargyl aldehyde diethyl acetal 128 gms. of propargyl aldehyde diethyl acetal,

ethyl mercaptan were heated together in a sealed tube, the temperature being raised to 120 C. over 3 /2 hours and maintained at 115 C.-120 C. for four hours. 'When cool the reaction mixture was poured on to crushed ice and the oil separated by extraction with ether. The ether extracts were dried over potassium carbonate, the solution filtered and the ether distilled oil. The residual oil was distilled twice under reduced pressure to yield the product boiling at 105 C. at 6mm. pressure.

(12) Preparation of p-ethyl-thio acrolein diethyl mercaptal from p-ethyl-thio acrolein diethyl acetal 33 gms. of s-ethyl-thio acrolein diethyl acetal, 40 gms. of ethyl mercaptan and 13 grns. of anhydrous zinc chloride were employed. The zinc chloride was added carefully to the cooled solution of the p-ethyl-thio acrolein diethyl acetal in th ethyl mercaptan. The reaction mixture was allowed to stand for 6 days and then poured into tracted with ether. The oil and the ether ex.

tracts were bulked and washed with water and 10% sodium carbonate solution, and finally dried over potassium carbonate. The ether solution was filtered and the solvent distilled oil. The product was obtained by distillation of the re-' sidual oil in vacuo, as a yellow oil, B. 10 mm. pressure.

' Exmm III Preparation of p-ethyl-thio acrolein diethyl mercaptal from propargyl aldehyde diethyl acetal gms. of propargyl aldehyde diethyl acetal, 60 ccs. of ethyl .mercaptanand 3.5 cos. of 50% aaueous'sulphuric acid (by volume) were mixed and allowed to stand for 12 days. At the end of this period ether was added andthe solution washed with water and sodium carbonate solution and dried over potassium carbonate. I The P. 190 C. at

. ether extracts were filtered and the solvent distilled off. Distillation of the residue under reduced pressure gave the required product and, as a low boiling fraction, some s-ethyl-thlo acro- -lein diethyl acetal.

EXAMPLE IV Preparation of fl-ethul-thio acrolein diethyl mercaptal from ,a-ethoxu acrolein diethyl ace- 16.8 gm's. of sodium mercaptide and 15 cos. of

ice water containing a small amount of dilute hydrochloric acid. The oil which precipitated was separated off and the aqueous liquors ex- 7.2 ms. of p-ethoxy acroleinacetal were mixed with 12 cos. of ethyl mercaptan and 1 cc. of a 50% aqueous sulphuric acid solution was added. The reaction mixture, which grew hot, was cooled and then allowed to stand at room temperature for 10 days. Ether was then added, the acid layer separated oil. and the ether extract, after washing with 10% sodium. carbonate solution, was dried over anhydrous potassium carbonate. The ether was distilled on and the residual oil distilled in vacuo, and the following fractions collected: (1) C., (2) 80-120 C., (3) -160 0., (4) -200" C. Fraction (4) was redistlllecl to, yield the required product.

What we claim is:

1. Compounds of the general formula: 

